Both the BuildCraft creative tab names are tab.machines and tab.facades. I'd fix it myself but i don't know what name you guys want to use. If you tell me I can create the PR myself.

Maybe "BuildCraft" would be ok instead of "tab"... Noticed it too when I was sorting my NEI list a bit, other mods have name according to mod name, but BC stood out by being "special" :D

oh....that just means I forgot the localization tags in the localization files.